Potential of Deficit and Supplemental Irrigation under Climate Variability in Northern Togo, West Africa

Agossou Gadédjisso-Tossou,Niels Schütze,Tamara Avellán

doi:10.3390/w10121803

Abstract

In the context of a growing population in West Africa and frequent yield losses due to erratic rainfall, it is necessary to improve stability and productivity of agricultural production systems, e.g., by introducing and assessing the potential of alternative irrigation strategies which may be applicable in this region. For this purpose, five irrigation management strategies, ranging from no irrigation (NI) to controlled deficit irrigation (CDI) and full irrigation (FI), were evaluated concerning their impact on the inter-seasonal variability of the expected yields and improvements of the yield potential. The study was conducted on a maize crop (Zea mays L.) at a representative site in northern Togo with a hot semi-arid climate and pronounced dry and wet rainfall seasons. The OCCASION (Optimal Climate Change Adaption Strategies in Irrigation) framework was adapted and applied. It consists of: (i) a weather generator for simulating long climate time series; (ii) the AquaCrop model, which was used to simulate the irrigation system during the growing season and the yield response of maize to the considered irrigation management strategies; and (iii) a problem-specific algorithm for optimal irrigation scheduling with limited water supply. We found high variability in rainfall during the wet season which leads to considerable variability in the expected yield for rainfed conditions (NI). This variability was significantly reduced when supplemental irrigation management strategies (CDI or FI) requiring a reasonably low water demand of about 150 mm were introduced. For the dry season, it was shown that both irrigation management strategies (CDI and FI) would increase yield potential for the local variety TZEE-W up to 4.84 Mg/ha and decrease the variability of the expected yield at the same time. However, even with CDI management, more than 400 mm of water is required if irrigation would be introduced during the dry season in northern Togo. Substantial rainwater harvesting and irrigation infrastructures would be needed to achieve that.

Highlights

The present world population of 7.3 billion will increase to 9.7 billion by 2050 [1]
The temperature is high during the dry season reaching 37 ◦ C and 26 ◦ C maximum and minimum temperatures, respectively, while, in the wet season, the maximum temperature is 30 ◦ C and the minimum temperature is close to 26 ◦ C (Figure 4a)
This argument is corroborated by Djaman and Ganyo [77] who found that the potential annual reference evapotranspiration—computed using2018, the10, Food and Agriculture Organization (FAO)-56

Summary

Introduction

The present world population of 7.3 billion will increase to 9.7 billion by 2050 [1]. FAO [3] estimates that agricultural production will have to rise by 60% by 2050 to meet the world’s projected demands for food and feed. In West Africa, Liniger et al [4] reported that food production should increase by 70% by 2050 to meet the necessary caloric requirements. A lack of available water for agricultural production, the energy sector, and other forms of anthropogenic water consumption is already harming several parts of the world. This lack of water is projected to become more severe with the growing population, rising temperatures, and altering

Methods

Results

Conclusion